A brand new biography on the late Anna Nicole Smith pours even more oil on an already high fire.

Playboy Playmate Anna Nicole Smith exerts undeniable fascination over many. The latest proof of this somewhat macabre interest in her life and death is “Blonde Ambition: The Untold Story Behind Anna Nicole Smith's Death,” by former NBC journalist Rita Cosby.

Anna Nicole passed away on February 8 this year. She was only 39. She had given birth to baby girl Dannielynn merely five months earlier. Around that same time, her 20-year-old son Daniel had died from a drug overdose.

Anna Nicole’s last few months were hardly happy ones. Rita Cosby’s book unveils even more of the unhappiness.

The journalist claims that Howard K. Stern, Anna’s lawyer and boyfriend at the time of her death, was actually having a relationship with Anna’s former boyfriend Larry Birkhead.

Birkhead eventually proved to be Dannielynn’s biological father, according to DNA tests conducted by judge’s order. Stern also claimed to be the baby girl’s father but once the tests showed it was not so, he did not press further for custody of the child.

Cosby takes her theory further, according to British tabloid The Daily Mail, claiming that the two men had in fact planned to share control over Anna’s fortune: Birkhead would obtain custody of the baby, while Stern would be named executor of her estate.

Anna Nicole’s fortune comes from a previous marriage the model, actress and television talk show host had.

Anna Nicole was only 26 when she married oil billionaire J. Howard Marshall, 63 years her senior. He passed away a year later, fuelling accusations that the luscious blonde had only married him for his money.

Anna had been in a legal battle for over a decade when she died, over Marshall’s $1.6 billion estate. Daughter Dannielynn could inherit a large portion of that fortune.

Both Stern and Birkhead obviously deny Cosby’s allegations and have even threatened to sue her. Birkhead is apparently enjoying parenthood and plans to throw a lavish princess-themed birthday party for his daughter, as he has already announced. She turns 1 on September 7.

Loving dad Birkhead had recently struck a deal with OK! magazine: exclusive coverage of Dannielynn’s first birthday in exchange for $1.7 million. It’s been scrapped though.

Another of Cosby’s theories, sounding like the script of a soap opera, is that Anna Nicole believed Stern had manipulated her son into taking the drugs that killed him.